Preparations for cleanups: con_font_op() is turned into a switch calling
con_font_{get,set,default,copy} depending on the operation required;
method ->con_font_op() also split, with NULL resulting in -ENOSYS on
operation in question.

Code that used to be in con_font_op() got slightly cleaned up after move
into new helpers (we are beginning to untangle the mess; there will be
more cleanups in the next patches).

Methods are currently using exact same arguments as old ->con_font_op().
That will change in subsequent patches, method by method (right now there's
a hell of a scary field reuse between them, making impossible to do any
static checks and practically begging for bugs).
Signed-off-by: Al Viro <viro@parcelfarce.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>